¹H and ¹³C NMR spectral assignments of 2′‐hydroxychalcones

Abstract

Chalcones are of interest to medicinal chemists because their structures can be easily modified with various functional groups. The syntheses and biological activities of chalcones from natural sources are well known. In this study, 24 2'-hydroxychalcones bearing methoxy substituents were synthesized, among which five are new. The NMR data for all synthesized chalcones are described for the first time. The complete assignments of the (1)H and (13)C NMR data can be used for the identification of newly discovered and widely isolated, synthesized chalcones.

1 H and 13 C NMR spectral assignments of 18 novel polymethoxylated hydroxynaphthopyrazolylchalconoids

“…[13] Results and discussion All of the polymethoxylated hydroxynaphthopyrazolylchalconoids shown in Fig. 2 are novel.…”

“…The procedure used to assign NMR data of derivative 12 containing six methoxy groups is as follows. The most downfield shifted 13 C peak was 173.6 ppm, which was assigned thioketone. The next downfield shifted 13 C peak was 158.1 ppm, which could be determined to be C-3 of pyrazoline (named as C-py-3).…”

“…[9] NMR spectra Synthetic polymethoxylated hydroxynaphthopyrazolylchalconoids, except derivative 4, were dissolved in deuterated dimethyl sulfoxide (DMSO-d 6 ) and derivative 4 was dissolved in deuterated chloroform (CHCl 3 -d). The 1 H and 13 C chemical shifts of the deuterated solvent were referenced to TMS. NMR samples were prepared at approximately 50 mM and transferred to a 2.5-mm NMR tube for spectral analysis.…”

“…For one-dimensional 1 H NMR spectra, the relaxation delay, 90°pulse, spectral width, number of data points, and digital resolution were 1 s, 11.8 μs, 5555 Hz, 32 K, and 0.339 Hz/ point, respectively. For 13 C NMR spectra, the same parameters were 3 s, 15.0 μs, 20 964 Hz, 64 K, and 0.640 Hz/point, respectively. For two-dimensional experiments such as correlation spectroscopy (COSY), heteronuclear multiple quantum correlation, and heteronuclear multiple bond correlation (HMBC), all data points (t 2 × t 1 ) were acquired with 2 K × 256.…”

“…1D), and synthesized 18 derivatives. Their NMR data and mass spectrometric (MS) data can help us to identify plant-derived polyphenols newly synthesized or isolated from natural sources in the future, thus, we report here the complete 1 H and 13 C NMR data and high-resolution MS data.…”